Here's my best advice: there are a bunch of books out there (for not very much money) about comics, scripting, the culture of comics, etc.

Look on Amazon, read through the preview pages, and invest in a couple that touch on what you're interested in doing, then devour them.

Why this advice?

Your question shows you've just put your pinkie toe into the deep end of the pool, and swimming lessons are required unless you want to drown a dozen time before catching up on what a few good books can help you with.

Someone correct me if I am mistaken, but the history of why these were all done separately (penciling, inking, coloring, lettering) was so that the book could be produced and therefore published faster.

Someone correct me if I am mistaken, but the history of why these were all done separately (penciling, inking, coloring, lettering) was so that the book could be produced and therefore published faster.

This is partially true. It comes from the early era of comic books (rather than just comics) when a publisher (like E.C. Gaines) would set up a studio with artists and writers to churn out material. Many artists would work together in the same room, and it was easy to pass pages back and forth. If one artist was better at people he would get the page for a bit. And another was better at backgrounds and he would get the page for a bit. Another was great at inking etc... They could pass the pages around and play to everyone's strengths. At this stage artists didn't ever get their names on or in the comics. Not all comics worked this way. Some had dedicated artists working on them, like Wonder Woman, but many were. If you have twenty artists in a room, they will work better and faster if they are all doing what they are good at.

This model (many artists, flexibly collaborating on pages) slowly faded out and was replaced with the structured roles we are familiar with today (penciller, inker, colorist, letterer). We have this structure in part to keep up the monthly pace, in part because artists tend to have things they are better at or like doing more, and in part because artists don't work in the same room anymore so you need a more structured way to divide up the labor (so you don't have any back-and-forth which would slow down production).